A crack caused a pipeline rupture leading to a wildfire in west-central Alberta in 2024, according to a report released on Thursday by the Transportation Safety Board of Canada (TSB). The incident occurred at around 10:45 a.m. on April 16, 2024, when a 36-inch natural gas pipeline owned by Nova Gas Transmission Ltd., a subsidiary of TC Energy Corp., ruptured about 36 kilometers northwest of Edson, Alberta.
An investigation revealed that stress corrosion cracking, influenced by soil conditions, degraded protective coating, and increased internal pressure, caused the pipeline rupture. Soil tests indicated microbiological activity that could corrode the pipeline’s steel, and the compromised external coating exposed the steel to environmental factors, promoting corrosion.
The report highlighted that the pipeline’s pressure was raised to its highest operating level on the day of the rupture, causing the crack to fully rupture. Interestingly, the TSB mentioned that the crack was identified two years earlier in a 2022 in-line inspection but was erroneously classified as non-reportable by analysts.
TC Energy did not include the crack in its inspection analysis or risk assessment due to the misclassification. Moving forward, TC Energy and its inspection vendors aim to enhance their processes to prevent such incidents in the future. Baker Hughes, the inspection service provider, expressed its commitment to improving inspection technologies and services based on the TSB report.
Post-rupture, the natural gas ignited, leading to an explosion and the creation of a seven-meter-deep crater. Approximately 20 meters of the pipe was expelled due to the explosion, with the largest piece of debris traveling 200 meters from the rupture site. The escaping gas burned until self-extinguishing at 1:45 p.m. that day, releasing nearly six million cubic meters of gas. The incident sparked a wildfire that consumed over 60 hectares, but thankfully, no injuries were reported.
The damaged pipeline section was replaced and resumed operation under reduced pressure on May 27, 2024.
